Munition

ABSTRACT

A rotatable airfoil munition comprising a hollow closed circular ring surrounding a central open area with the detonation system and military filling material positioned within the hollow ring. the munition projectile consists of an aerodynamic lifting body of a thick ring wing geometry which uses spin imparted to it from a launching means for its gyroscopic stability, thus permitting a relatively flat trajectory as compared with the prior art munitions which require a loft trajectory for substantially the same range. The combination of aerodynamic stability characteristics and high spin rate (e.g. above 2,000 rpm) results in both a flat trajectory and extended range capability as compared to a conventional ballistic projectile for the same initial subsonic launch velocity.

United States Patent [191 Flatau 1 MUNITION Abraham Flatau, 2003Stockton Rd., Joppa, Md. 21085 22 Filed: July 17, 1972 211 App]. No.:272,252

Related U.S. Application Data [63] Continuation-impart of Ser, No.105,751, Jan. 6,

1971, abandoned.

[76] Inventor:

[52] U.S. Cl. 102/93; 102/56; 102/67; 102/92.1; 244/31 [51] Int. Cl.F42b 13/12 [58] Field of Search 102/2, 6, 7.2, 38, 56, 102/64-67, 92.1,93; 244/323, 3.1

[56] References Cited UNITED STATES PATENTS 2,362,414 11/1944 Simpson102/7.2 2,371,510 3/1945 Fagerlund 102/67 2,386,054 10/1945 McGee 102/932,624,281 1/1953 McNally 244/323 2,918,006 12/1959 Zborowski. 102/563,264,776 8/1966 Morrow 46/74 1 Apr. 15, 1975 3,738,279 6/1973 Eyre102/94 Primary Examiner-Verlin R. Pendegrass Attorney, Agent, orFirm-Robert P. Gibson; Nathan Edelberg; Robert W. Church [57] ABSTRACT Arotatable airfoil munition comprising a hollow closed circular ringsurrounding a central open area with the detonation system and militaryfilling material positioned within the hollow ring. the munitionprojectile consists of an aerodynamic lifting body of a thick ring winggeometry which uses spin imparted to it from a launching means for itsgyroscopic stability, thus permitting a relatively flat trajectory ascompared with the prior art munitions which require a loft trajectoryfor substantially the same range.

The combination of aerodynamic stability characteristics and high spinrate (cg. above 2,000 rpm) results in both a flat trajectory andextended range capability as compared to a conventional ballisticprojectile for the same initial subsonic launch velocity.

14 Claims, 9 Drawing Figures FATENTEBAFR I 5l975 l III 6.

PRIOR ART JHIA-LDED z!" MUNITION This application is acontinuation-in-part of Ser. No. 105,751, filed January, 6, i971, andnow abandoned.

The invention described herein may be manufactured, used and licensed byor for the Government for governmental purposes without the payment tome of any royalty thereon.

This invention relates to significant improvement in the rangeofmunition projectiles while providing a relatively flat trajectory ascompared to the conventional ballistic trajectory.

To obtain extended range, current projectiles, from shoulder firedgrenades to artillery munitions, have been using a rocket boost whichhas been added to the basic munition projectile. The rocket motorarrangement has increased the range approximately one-third more than isobtained without the rocket.

The object of this invention is to provide an extended range capabilitywithout the need for the additional weight and cost of the rocket motorarrangement.

A further object of this invention is to provide a munition projectilewhose terminal ballistics capability, on a lethality per pound munitionbasis, represents a sig nificant increase over conventional projectiles.

This invention is directed to a body of revolution forming a closedcircular airfoil warhead, Ring Airfoil Munition, with a hollowconfiguration surrounding a central opening rotating about an axis inthe general direction of its trajectory toward the impact area. Thehollow section houses the payload and explosive train.

This invention relates to a new munition configuration based on a ringairfoil or ring wing whereby a body of revolution generated by theairfoil cross section rotated 360 about an axis beneath and parallel tothe longitudinal direction of the airfoil cross section.

The principal object of this invention is to provide a munition whichwill be more effective to overcome enemy resistance.

Another objective is to provide a munition which will be more effectivein utilizing direct-in-line fire trajectory.

Another objective is to provide a means for greater destruction of thetarget area without materially increasing the payload.

Another object is that the inventive warhead may be fired from anyconventional launcher which utilized a sabot cartridge.

Still a further objective is to provide a ring airfoil munition with alow angle of elevation for its primary trajectory.

Various developments have been made in the art of warfare for destroyingmateriel and personnel by means of bullets, mortars, and grenades. Thesemeans have a range that is limited to their ballistic properties. Manyof these means have necessitated the use of launching systems requiringthe projectile to have an angle of elevation above the ground level upto about 45 in order to achieve maximum range. In most instances formaximum range, the conventional projectile cannot be fired on a directline or even at small elevation angles such as 6.

The conventional projectiles have a basic deficiency in that mid tomaximum ranges cannot be achieved without resorting to the normal lofttrajectories resulting from relatively high elevation angles, forexample 30 to 45.

The Army's standard shoulder-fire grenade launcher (M-79) and the 40mm(M-406) shoulder-fired grenade cannot be fired for maximum range atsmall angles of elevation.

ln heavy overhanging jungle canopy, the soldier in attempting to hit thetarget from a medium to maximum range must fire with the normal arch orloft trajectory. This has resulted, in many instances, in the projectile striking or grazing this foliage and being deflected from thedesired trajectory. In other words, a relatively flat trajectory wouldhave been desirable to avoid the interference effects of thisenvironment.

The aeroballistic configuration of the present warhead overcomes theformer limitations of the loft trajectory and permits a 5 to 7 angle ofelevation of the launcher for substantially the same range as the 35angle of elevation required for the 40mm M-39 grenade system.Additionally, the inventive warhead may also be launched for a lofttrajectory if desired.

The inventive projectile warhead provides major improvements intrajectory capability with increased range by a factor of 2 or more forthe same launch velocity and weight of the projectile as the M-406grenade. The inventive warhead has demonstrated a significant increasein lethality for the same amount of HE (high explosive) as used in theconventional 40mm grenade (M-406).

The unique aerodynamic characteristics of the ring airfoil configurationresults in permitting the soldier to fire on a substantially direct lineto the target area.

The configuration of the present invention possesses aerodynamicproperties which are not available in conventional ballisticprojectiles. ln flight, the munition is rotating about its axis ofsymmetry which is central to the body of revolution formed by rotatingthe airfoil cross section about the same axis. The spin rate shouldexceed about 2,000 rpm, and preferably should far exceed 2,000 rpm. Therotational motion produces gyroscopic stability so that although theattitude ofthe projectile tends to remain relatively constant, the angleof the ring airfoil projectile along the trajectory produces a liftforce which partly offsets the influence of gravity. This is achieved byusing an essentially neutral static aerodynamic moment or stabilitycharacteristic C, o: Additionally, the ring airfoil projectile has muchlower drag than the conventional M-406 grenade. Thus the combination oflift and low drag produces a relatively flat trajectory and an extendedrange for any given (sub-sonic) launch velocity while firing at lowlaunch angles.

The airfoil cross-sectional contour and ring arrangement result in moreuniform fragment distribution over a larger area than can be achievedwith the M406 grenade. The ring airfoil configuration can therefore beutilized in a tactical role wherein it may be either exploded in air inthe proximity of the target or exploded by direct impact with thetarget.

The fragment spray pattern of the M-406 grenade is generally limited tothe rearward direction only and totals approximately The arena testsindicated directly the fragment spray patterns and distributionresulting from the Ring Airfoil Grenade, inventive structure, with anotched wire warhead. The lethality as developed from the arena dataresults in a substantial increase for the inventive warhead as comparedto the M-406. This is due, in part, to both the increase in the numberof available fragments resulting from the ring airfoil geometry and theabsence of any shielding in the structure, which provides the inventivemunition with a significant increase in fragment distribution ascompared to the M 406. FIGS. 1 and 3 illustrate the spray patterns anddistribution of fragments resulting from the arena tests.

FIG. I is a longitudinal sectional view of FIG. 2.

FIG. 2 is an elevated view of the prior art grenade;

FIG. 3 is a perspective view partially broken away exposing thecross-sectional view of the structure of this invention;

FIG. 4 is a cross-sectional view of the projectile and sabot;

FIG. 5 is a cross-sectional view of the sabot and cartridge;

FIG. 6 is a perspective view of the inventive projectile;

FIG. 7 is an enlarged cross-sectional view of the inventive structure;

FIG. 8 and FIG. 9 are perspective views illustrating an inner ring fuzeand a sector fuze, respectively.

In FIGS. 1, 2, 3 and 6, the straight arrows indicate the path of flight.In FIG. 6, the curved arrow indicates the direction of rotation.

The warhead is a self-contained unit and the configuration, rather thanbeing provided with any specific payload. is adaptable to the variousmilitary filling material useful in warfare. Further, as is conventionalwith such military hardware, the warhead, in accordance with thisinvention, FIGS. 3 and 7, is provided internally with a fuze 7, positionin the aft fuze ring 5. initiating the booster lead 11, then the booster13, which sets off the explosive fill 15, and this in turn produces theforce that breaks up the exterior surface of l and expells the preformedfragments. These aforesaid internally functional elements areconventional and the purpose and manner of operation thereof are wellknown to those skilled in the art. Other fuse locations are contemplatedincluding for example, an inner ring fuze such as is illustrated in FIG.8 and sector fuzing as is illustrated in FIG. 9.

It is within contemplation of this invention that other internalconventional elements emloyed for initiating detonation of militaryhardware can be utilized in the structure of this invention.

Contemplated in this invention are the other various state-of-the-artfuzes functioning with time, impact, proximity, or command, providingsafe separation from the launcher prior to arming in flight.

The present invention is superior to prior art devices for destroying orincapacitating military objectives by means of highexplosive-fragmentation, incendiary ma terials, or incapacitatingmatter.

The projectile may be filled with chemical materials which will yield avapor when released from the projectile structure. Examples of wellknown agents are phosgene, mustard, a-chloroacetophenone. Otherprojectile filling components may yield a smoke, for example, whitephosphorus, sulfur trioxide with chlorosulfonic acid, or incendiarymaterial such as thermit which is black non-oxide mixed with aluminum orwhite phosphorus.

The airfoil cross-sectional utilized in the ring airfoil grenade israther thick; that is, in order of to of the chordal dimension.preferably about 25-30%, at its point of maximum thickness. The emphasison this amount of thickness is to allow sufficient explosive to beloaded within the airfoil warhead and obtain a relatively high charge tomass ratio. This is the ratio by means of which the basic explosive andfragment velocity characteristics may be predicted as well as provide abasis for performance comparison with other warheads. The ring airfoil'sforward (leading) and rearward (trailing) edges are shaped so that theleading edge radius is noticeably greater in radius than the trail' ingedge which forms part of the aft fuze ring in the fuzing modeillustrated by FIG. 7. More specifically, the airfoil cross sectiondepicted in FIG. 7 is substantially an enlargement of the cutout sectionof FIG. 3, wherein the lead line of numeral 1 engages the major outersurface of the airfoil cross section and the lead line of numeral 3engages the major inner surface of the airfoil cross section. Theleading edge of the airfoil cross section is that uppermost portionshown in FIG. 7 where the major surfaces smoothly join. The trailingedge is that portion of the airfoil cross section, lowermost in FIG. 7,where the major surfaces converge to a small radius.

Fabrication and arena testing of explosive items utilizing the steelnotched wire fragments has shown that overall diameters of 2 to 2.75inches and chordal dimensions of l to l.4 inches produced desiredresults. Low aspect ratios, that is, span or diameter to chordal value,that are near unity do not result in good aerodynamic properties.

FIG. 2 is an elevated view of the prior art grenade (40mm, M-406) with 2designating the exterior casing, the notched wire ball for fragmentation4, and the fragments 6 expelled upon detonation of the projectile.

FIG. I, the longitudinal view of FIG. 2, illustrates the fragment spraypattern with the exterior case 2, fuze 8, explosive l0, notched wireball for fragmentation 4, ll lustrating the shielding effect over atleast 60% of the fragmenting ball. This shielding effect reduces boththe fragment velocity, lethal radius, and area of destruction of theprojectile outside of the unshielded zone.

In FIG. 3, numeral 27 designates the warhead exposing a cross-sectionalview of the internal structure. FIG. 3 illustrates the spray pattern tobe 360 rotational, that is, no shielding effect, of the entire exteriorsurface of the warhead expelling the preformed fragments in alldirections.

FIG. 7 is an enlarged cross-view more clearly revealing the internalcomponents and the three major portions forming the warhead, fragmentingouter unit I, inner unit 3, and aft fuze ring 5 located in the trailingedge of the warhead. The outer unit is internally preformed for moreprecise fragmentation. The three portions are joined together byconventional means such as epoxy bonding agents or other metal to metalbinding agents which will cause these portions to be structurallyintegral under the conditions of use. If desired, the warhead can beunitized by conventional metal joining processes.

FIGS. 8 and 9 illustrate ring and sector fuzing, respectively, whichfuzing systems might be incorporated into the warhead, the structuralcomponents of the warhead being always appropriate to the fuzingselected and, of course, consistent with aerodynamic stabilityrequirements.

FIG. 5 is a cross-sectional view of cartridge and sabot, which is loadedinto a conventional sabot launcher sized for this projectile. Thecircular cartridge-sabot comprises an outer wall housing 20, a casingZl, circular primer 22, which is in alignment with the firing pin of thetrigger mechanism of the launcher, not shown, ignites the circularpropellant 23 developing a sufficient amount of power actuating thecircular piston 24, driving the ring 25, which is attached to the sabot26 containing the inventive warhead 27. The inner portion 31 of thecasing encloses aforesaid primer. propellant and a portion of thepiston, so that upon the forward motion of the piston, the warhead willnot rotate within the sabot as it moves down the barrel of the launcher.not shown. The sabot contains projections 29 and 28, FIG. 4, whichengage the rifling section of the launchers barrel as the sabot ispropelled toward the muzzle of the launcher.

In use, the firing pin will hit directly the primer and in turn ignitesthe propellant powder. The igniting powder moves the piston forwardgiving the sabot containing the munition 27 the initial push forward andengaging the rifling band along the barrel of the launcher therebyrotating the sabot and munition. As the spinning sabot leaves thelauncher, the centrifugal forces generated by the spin act on themultiple partially split forward sabot section and together with airdrag rapidly separate the sabot from the projectile, thus allowing theprojectile to fly on its designated trajectory.

Although the sabot has been illustrated and described, it should beappreciated that the present invention relates entirely to the minitionprojectile, other means of obtaining the desired launch velocity andspin rate are contemplated, including for example, an integrated riflingband in the area of maximum projectile diameter, the band beingcontoured to the airfoil cross section. Other alternative methods mayinclude preengraved (rifling) surfaces, again in the area of maximumrifling surfaces.

In any event, the munition projectile of the present invention islaunched with a conventional propellant at sub-sonic velocities beyond200 ft/sec at spin rates well exceeding those of comparable munitions.In an absolute sense, the initial spin rate will always exceed about2,000 rpm. For specific sizes and applications, an optimum spin may beselected based on a flight dynamics analysis which includes suchparameters as projectile mass, launch velocity, range, and deflection.During the flight of the munition along its trajectory its rotatingmotion produces gyroscopic stability. The attitude of the projectilealong the trajectory and its airfoil shaping produces lift to partiallyoffset gravity. This results in a flatter trajectory as compared to theconventional ballistic trajectory. When the munition explodes, theforces within the rupturable surfaces cause the prescored outer casingor exterior wall to fragment resulting in expelling the small fragmentsoutward at high initial velocity distributing the fragments. In the useof incapacitating agents as the payload, the agents will en gulf themilitary target.

The assembly ofthe finalized airfoil warhead (shown in FIG. 7) comprisesthe steps ofjoining units 1 and 3, thus forming a forward portion andhollow section of the partial airfoil configuration, filling the formedcavity with the desired filling material 15, positioning the detonationsystem comprising the booster, booster lead, stab detonator and fuze,and joining the rear section by means of the aft fuze ring 4, thuscompleting the trailing edge of the airfoil configuration and obtaininga structurally integral unit. Other structural arrangements and assemblytechniques are, of course, required for other fuzing arrangements, suchas for example. the fuzing modes of FIGS. 8, 9.

The munition may be launched or directed toward its impact area in ahand-held weapon. shoulder-fired or motorized mounted weapon system. orfrom a low speed airborne vehicle.

The warhead is fabricated from substances conventional in militaryhardware, for example, steel, aluminum, magnesium, or alloys. For usewith certain agents such as O-chlorobenzilidene malononitrile, a softmaterial such as rubber or soft plastic may be used for forming thewarhead. The sabot-cartridge may be constructed from high densitypolymeric material such as polyethylene or polypropylene. The cartridgecasing may be aluminum or other light-weight material, for example, highdensity polyethylene or polypropylene.

It is also within the scope of this invention that the fragmentationportion of the warhead comprises the spirally wound notched wire asfound in the prior art structure ofthe M-406 grenade. However, it wasfound that utilizing the notched wire results in the outer surface ofthe inventive airfoil grenade having surface irregularities thuseffecting aerodynamic characteristics. The preformed fragments of thewarhead are accomplished by prescoring or engraving the inner surface ofunit 1, FIGS. 3 and 7, thus achieving a smooth exterior surfaceresulting in the desired aerodynamic properties giving rise to therequired stability and range while ob taining the desired fragment sizeand configuration.

The above description, including exemplary size ranges, has largely beendirected to what constitutes an antipersonal munition. However, withincontemplation of this invention is usage of the munition in anantimaterial role, for which larger diameter sizes may be preferred, andalso usage therein with specific warheads adapted thereto such as massfocus, or High Explosive Plastic (HEP). However, some warheads, thoughfeasible, may not be superior to conventional projectiles, for example,shaped charges. To obtain a meaningful armor penetration capability fora shaped charge (hollow charge) warhead within the ring airfoil, itwould be necessary to have ring airfoil units of outside diameter inexcess of 8 inches, thus making for an unwieldy size as well as theincreased weight. Comparatively, this large a ring airfoil munitioncould not nearly equal the penetration capability of a conventionalshaped charge projectile having the same weight.

What is claimed is:

l. A ring shaped airfoil munition projectile to be launched from a guncomprising: a means of producing high lift, low drag, and extendedrange, said means consisting of an annulus having essentially acontinuous unbroken exterior airfoil cross section, said annulus hav ingmajor annular outer and inner substantially curvi linear surfaces whichform the diametrical extents of said projectile with at least one ofsaid curvilinear surfaces so configured to provide aerodynamic lift forsaid projectile, and said annulus having leading and trailing edgesjoining said major outer and inner surfaces defining the longitudinalextent of said projectile; and means for rotating said projectile.

2. The projectile of claim 1 wherein same is hollow and has fuse meansand is filled with material selected from the group consisting ofexplosives, incendiary agents and incapacitating agents.

3. The munition of claim 2 wherein the internal sur face of saidprojectile is scored.

4. The munition of claim 1 wherein the projectile exterior is metal.

5. The munition of claim 1 wherein the projectile ex terior is ofpolymeric material.

6. The munition of claim I wherein both the major outer and innersurfaces are configured to provide aerodynamic lift for said projectile.

7. The munition of claim 1 wherein the rotating means is transmitted bymeans of a sabot.

8. The munition of claim 1 wherein the rotating means is an integratedrifling band imposed upon a por' tion of the lifting body outer surface.

9. The munition of claim 1 wherein the rotating means is a preengravedrifling surface on the lifting body.

10. A ring shaped airfoil munition projectile to be launched from a gunhaving means for producing high lift, low drag, and extended range, saidmeans consisting of: an annulus having essentially a continuous unbrokenexterior airfoil cross section, said annulus having annular major outerand inner substantially curvilinear airfoil surfaces defining thedimetrical extent of said projectile, with at least one of said surfacesso configured to provide aerodynamic lift, and said surfacesconcentrically defining an axis serving in common as the axis of symetryand the axis of gyroscopic rotation. and said annulus having leading andtrailing edges joining said surfaces and defining the longitudinalextent of said projectile; so that upon rotating said projectile on saidaxis at at least 2000 RPM and propelling it from said gun, leading edgefirst, in the direction of said axis through the atmosphere the said atleast one of said surfaces causes lift which together with low dragairfoil shaping results in a relatively flat trajectory and extendedrange.

ll. The munition of claim 10 wherein it is made from the groupconsisting of metals, alloys thereof and polymer materials.

12. The munition of claim 10 wherein the projectile is hollow and has aninterior provided with means and filling material selected from thegroup consisting of explosives, incendiary agents and incompacitatingagents.

13. The munition of claim 12 wherein the projectile interior surface isscored for fragmentation purposes.

14. A munition to be fired by a gun means comprising a tube-like casinghaving at one end thereof a ring shaped airfoil projectileconcentrically disposed in said casing and said projectile having meansof producing high lift, low drag, and extended range, said meansconsisting of an annulus having essentially a continuous unbrokenexterior cross section airfoil, said annulus having major outer andinner airfoil surfaces at least one configured for providing aerodynamiclift and joined by leading and trailing edges with said surfaces beingsubstantially concentric with said casing and said leading edge beingoutermost relative to said casing, and having near the other end(thereof) of said casing detonation and propelling means for rotatingsaid projectile in the plane of its annulus and ejecting it from saidcasing and allowing it to enter into trajectory.

1. A ring shaped airfoil munition projectile to be launched from a guncomprising: a means of producing high lift, low drag, and extendedrange, said means consisting of an annulus having essentially acontinuous unbroken exterior airfoil cross section, said annulus havingmajor annular outer and inner substantially curvilinear surfaces whichform the diametrical extents of said projectile with at least one ofsaid curvilinear surfaces so configured to provide aerodynamic lift forsaid projectile, and said annulus having leading and trailing edgesjoining said major outer and inner surfaces defining the longitudinalextent of said projectile; and means for rotating said projectile. 2.The projectile of claim 1 wherein same is hollow and has fuse means andis filled with material selected from the group consisting ofexplosives, incendiary agents and incapacitating agents.
 3. The munitionof claim 2 wherein the internal surface of said projectile is scored. 4.The munition of claim 1 wherein the projectile exterior is metal.
 5. Themunition of claim 1 wherein the projectile exterior is of polymericmaterial.
 6. The munition of claim 1 wherein both the major outer andinner surfaces are configured to provide aerodynamic lift for saidprojectile.
 7. The munition of claim 1 wherein the rotating means istransmitted by means of a sabot.
 8. The munition of claim 1 wherein therotating means is an integrated rifling band imposed upon a portion ofthe lifting body outer surface.
 9. The munition of claim 1 wherein therotating means is a preengraved rifling surface on the lifting body. 10.A ring shaped airfoil munition projectile to be launched from a gunhaving means for producing high lift, low drag, and extended range, saidmeans consisting of: an annulus having essentially a continuous unbrokenexterior airfoil cross section, said annulus having annular major outerand inner substantially curvilinear airfoil surfaces defining thedimetrical extent of said projectile, with at least one of said surfacesso configured to provide aerodynamic lift, and said surfacesconcentrically defining an axis serving in common as the axis of symetryand the axis of gyroscopic rotation, and said annulus having leading andtrailing edges joining said surfaces and defining the longitudinalextent of said projectile; so that upon rotating said projectile on saidaxis at at least 2000 RPM and propelling it from said gun, leading edgefirst, in the direction of said axis through the atmosphere the said atleast one of said surfaces causes lift which together with low dragairfoil shaping results in a reLatively flat trajectory and extendedrange.
 11. The munition of claim 10 wherein it is made from the groupconsisting of metals, alloys thereof and polymer materials.
 12. Themunition of claim 10 wherein the projectile is hollow and has aninterior provided with means and filling material selected from thegroup consisting of explosives, incendiary agents and incompacitatingagents.
 13. The munition of claim 12 wherein the projectile interiorsurface is scored for fragmentation purposes.
 14. A munition to be firedby a gun means comprising a tube-like casing having at one end thereof aring shaped airfoil projectile concentrically disposed in said casingand said projectile having means of producing high lift, low drag, andextended range, said means consisting of an annulus having essentially acontinuous unbroken exterior cross section airfoil, said annulus havingmajor outer and inner airfoil surfaces at least one configured forproviding aerodynamic lift and joined by leading and trailing edges withsaid surfaces being substantially concentric with said casing and saidleading edge being outermost relative to said casing, and having nearthe other end (thereof) of said casing detonation and propelling meansfor rotating said projectile in the plane of its annulus and ejecting itfrom said casing and allowing it to enter into trajectory.